Brown: one year on, 20 points behind, says exclusive ICM poll

Gordon Brown faces a damning verdict from voters ahead of his first anniversary in power, according to a new Guardian/ICM poll. It suggests that his prime ministership has been a disappointment: 74% of those questioned say that he has been a change for the worse compared with Tony Blair, and only 24% think Labour has a chance of winning the next election while he remains leader.

The poll also gives the Conservatives a record 20-point lead over Labour, six points up on last month. Labour support has fallen two points to 25%, the lowest recorded in the ICM polls, which began in 1984.

Conservative support, at 45%, is at a 20-year high. That would give David Cameron a landslide victory as big as Labour's win in 1997, with some 400 seats. Labour might be reduced to well under 200 MPs, with many ministers losing their seats. The Tories would retain Crewe and Nantwich, won in a byelection last month, while Labour would lose previously safe seats such as Wakefield.

Conservative support has increased four points since last month's Guardian/ICM poll, and three points since another more recent ICM poll. Labour support has dropped two points since the last Guardian survey.

Liberal Democrat support, at 20%, is two points down but remains only five points behind Labour, the narrowest gap on record. Backing for other parties, at 10%, is up one on last month, partly because of the strong nationalist performance in Scotland.

The figures record the dramatic decline in Labour fortunes since Brown took over as leader. A year ago, Labour had a four-point lead over the Tories in the June Guardian/ICM poll. Support for the party, at 39%, was 14 points higher than today.

Voters also think Brown has failed personally as prime minister. Asked to rate his performance on a scale of one to 10, voters give Brown only 3.94 on average. Almost a quarter, 23%, give him a one.

Even people who remain loyal to Labour are unconvinced by the prime minister's performance: only 4% give him full marks. Among people who voted Labour in 2005, many of whom now back other parties, 54% give him five out of 10 or less.

Attitudes are much the same among all socio-economic groups, all parts of the country and between men and women.

A majority of people who backed Labour at the last election, 57%, also say that they do not think the party can win again with Brown as leader. Even among current Labour supporters, 38% think Brown cannot win.

Labour is shedding support to both the Conservatives and the Liberal Democrats: 17% of people who backed the party in 2005 are thinking of backing the Tories instead while 7% may vote Lib Dem.

The government has struggled to retain even its core supporters over the last year. Among people who voted Labour in 2005, only 3% of voters say that their impression of the prime minister and his party has gone up, while 46% say that it has gone down.

The government is also suffering from the economic downturn. Only 13% agree with ministerial claims that Britain's problems are the result of global difficulties. Most feel that the government should take some, or most, responsibility: 86% think that government decisions have played a part, and 40% think the government is mainly or wholly to blame. Even among people who backed Labour in 2005, 74% think that the government is at least partly at fault.

 ICM interviewed a random sample of 1,000 adults aged 18+ by telephone between June 20 and 22 2008. Interviews were conducted across the country and the results have been weighted to the profile of all adults. ICM is a member of the British Polling Council and abides by its rules.